Abdominal exercise machine



FIG. 1 is a rear view of an abdominal exercise machine device embodying the design.

FIG. 2 is a front view thereof.

FIG. 3 is a side view thereof.

FIG. 4 is an opposite side view thereof;

FIG. 5 is a top view thereof.

FIG. 6 is a bottom view thereof; and,

FIG. 7 is a perspective view thereof. 

The ornamental design for an abdominal exercise device, as shown and described. 